[求助]新手求助~（关于初级的神经网络问题） [复制链接]

各位大虾，我在网上看到的教程里的一个程序段，本来想要试试看的： e V#H"fM  
net=newff([-1 2; 0 5],[3,1],{'tansig','purelin'},'traingd'); L M[<?`%p  
net.trainParam.show = 50; ~Fh(4'  
net.trainParam.lr = 0.05; hR2.w/2j  
net.trainParam.epochs = 300; _L ].n)b  
net.trainParam.goal = 1e-5; k5/}S@F8  
p = [-1 -1 2 2;0 5 0 5]; $6[]c)(  
t = [-1 -1 1 1]; G<I5%Yo6G  
net=train(net,p,t); 'tj4;+xf^  
TRAINGD, Epoch 0/300, MSE 1.59423/1e-05, Gradient 2.76799/1e-10 r}w 9?s^rB  
TRAINGD, Epoch 50/300, MSE 0.00236382/1e-05, Gradient 0.0495292/1e-10 SQ[}]Tm;n  
TRAINGD, Epoch 100/300, MSE 0.000435947/1e-05, Gradient 0.0161202/1e-10 &-9D.'WzP  
TRAINGD, Epoch 150/300, MSE 8.68462e-05/1e-05, Gradient 0.00769588/1e-10 xYq8\9Qb  
TRAINGD, Epoch 200/300, MSE 1.45042e-05/1e-05, Gradient 0.00325667/1e-10 ;DOz92X
94  
TRAINGD, Epoch 211/300, MSE 9.64816e-06/1e-05, Gradient 0.00266775/1e-10 VrG|/2  
TRAINGD, Performance goal met. 9v A`\\9  
a = sim(net,p) 1Ppzch7  
plot(p,t,p,a,'o') JP]K\nQx'  
但是为什么老是报错： )/Vr 5b@  
??? Input argument "net" is undefined. *Bj G3Jc5